1. Field of the Invention
This invention relates to a nitride semiconductor laser element and a method for manufacturing the same.
2. Background Information
As shown in JP-2009-152276A and JP-2010-68007A, an example of a nitride semiconductor laser element is one in which a nitride semiconductor layer is formed on a substrate, and an insulating film and an electrode are formed on the top face of this. An end face protective film is formed on the cavity plane thereof. As shown in JP-2007-59897A, the end face protective film is sometimes formed so that it goes around the top face of the nitride semiconductor layer.
The end face protective film is preferably formed so that it will have good adhesion to the cavity plane not only during formation, but also after drive time has elapsed, and the material, film thickness, and so forth are adjusted to this end. It has been disclosed that with a nitride semiconductor laser element, forming an end face protective film composed of a nitride and hexagonal crystals reduces the damage to the cavity plane, or improves adhesion between the cavity plane and the end face protective film (JP-2009-152276A and JP-2010-68007A).
However, when an end face protective film is actually formed from such materials and then subjected to an expected-life characteristics test, there are sometimes elements with poor service life characteristics, in which a sudden rise in drive current is seen. With an element with poor service life characteristics, degradation is observed in the nitride semiconductor layer near the cavity plane.